Hyaloid body | definition of hyaloid body by Medical dictionary Hyaloid body | definition of hyaloid body by Medical dictionary 1. the largest and most important part of any organ. 2. any mass or collection of material. acetone b's ketone bodies . alkapton b's a class of substances with an affinity for alkali, found in the urine and causing the condition known as alkaptonuria . The compound commonly found, and most commonly referred to by the term, is homogentisic acid . amygdaloid body a small mass of subcortical gray matter within the tip of the temporal lobe, anterior to the inferior horn of the lateral ventricle of the brain. It is part of the limbic system. aortic b's small neurovascular structures on either side of the aorta in the region of the aortic arch, containing chemoreceptors that play a role in reflex regulation of respiration. asbestos b's golden yellow bodies of various shapes, formed by the deposition of calcium salts, iron salts, and proteins on a spicule of asbestos , found in the lungs, lung secretions, and feces of patients with asbestosis .

Aschoff b's submiliary collections of cells and leukocytes in the interstitial tissues of the heart in the myocarditis that accompanies rheumatic fever ; called also Aschoff's nodules. asteroid body an irregularly star-shaped inclusion body found in the giant cells in sarcoidosis and other diseases. Barr body sex chromatin . basal body a modified centriole that occurs at the base of a flagellum or cilium. carotid b's small neurovascular structures lying in the bifurcation of the right and left carotid arteries, containing chemoreceptors that monitor the oxygen content of the blood and help to regulate respiration. ciliary body see ciliary body . Donovan b's encapsulated bacteria (Calymmatobacterium granulomatis) found in lesions of granuloma inguinale , visible when a Wright-stained smear of infected tissue is viewed under a microscope. body dysmorphic disorder a somatoform disorder in which a normal-appearing person is either preoccupied with an imagined defect in appearance or is overly concerned about a very slight physical anomaly. See also body image . Called also dysmorphophobia . fimbriate body corpus fimbriatum .

foreign body a mass of material that is not normal to the place where it is found. fruiting body a specialized structure of certain fungi that produces the spores. geniculate body, lateral either of the two metathalamus eminences, one on each side just lateral to the medial geniculate bodies, marking the termination of the optic tract. geniculate body, medial either of the two metathalamus eminences, one on each side just lateral to the superior colliculi, concerned with hearing. hematoxylin body a dense, homogeneous particle, easily stainable with hematoxylin , consisting of nuclear material derived from an injured cell together with a small amount of cytoplasm. Hematoxylin bodies occur in systemic lupus erythematosus . Lymphocytes that ingest such particles are known as le cells . Called also LE body. Howell's b's (Howell-Jolly b's) smooth, round remnants of nuclear chromatin seen in erythrocytes in megaloblastic and hemolytic anemia, in various leukemias and after splenectomy.

body image the total concept, including conscious and unconscious feelings, thoughts, and perceptions, that a person has of his or her own body as an object in space independent and apart from other objects. The body image develops during infancy and childhood from exploration of the body surface and orifices, from development of physical abilities, and from play and comparison of the self with others. Changes in body image are particularly important in adolescence when attention is focused on appearance and attractiveness and relations with others. Body image is strongly influenced by parental attitudes that give the child a perception of certain body parts as good, clean, and attractive, or bad, dirty, and repulsive. The evolution of body image continues throughout life and incorporates such factors as a person's style of dress, hair style, and use of makeup, which symbolize social and professional status and other feelings about the self. Many clinical syndromes involve disturbances of body image. Disturbed body image is a nursing diagnosis that was approved by the North American Nursing Diagnosis Association, defined as confusion in the mental picture of one's physical self. Surgery or trauma involving disfigurement or loss of a body part can be very threatening to a patient.

Diseases involving a loss of body function, such as stroke syndrome, paraplegia, quadriplegia, coronary heart disease, and bowel or bladder incontinence, and diseases involving disfiguring skin lesions or the feeling of “rotting away” as in cancer or gangrene, can all cause changes in body image. Body image is frequently disturbed in schizophrenia, and patients may feel that their body or its parts are changing in size or shape or are ugly or threatening. Rape or violent physical assault can disturb the feeling of being secure in one's own body. Changes in body image involving sexual attractiveness or sexual identity, such as surgery or trauma involving the genitals or breasts and tubal ligation, hysterectomy, or vasectomy, can be especially difficult for the patient to deal with. Intrusive therapeutic or diagnostic procedures, such as insertion of a nasogastric tube, bladder catheterization, administration of intravenous fluids, endoscopy, and cardiac catheterization, can also threaten a patient's body image. The reaction of a patient to an alteration in body image can include mourning the loss of the former body image, fear of rejection by significant others, hostility, and experiencing of “phantom” sensations from missing body parts.

Patients with less ability to cope with their loss may respond with denial or depression. This can lead to a rejection of the altered body image and feelings of depersonalization that can involve avoidance of interpersonal contact and an unwillingness to discuss the deformity or to accept corrective medical treatment or vocational rehabilitation. inclusion b's round, oval, or irregular-shaped bodies in the cytoplasm and nuclei of cells, as in disease caused by viral infection, such as rabies, smallpox, and herpes. lamellar body keratinosome . Lafora's b's intracytoplasmic inclusions consisting of a complex of glycoprotein and acid mucopolysaccharide; widespread deposits are found in Lafora's disease , a type of epilepsy. LE body hematoxylin body. Leishman-Donovan b's round or oval bodies found in the reticuloendothelial cells, especially those of the spleen and liver, in kala-azar ; they are nonflagellate intracellular forms of Leishmania donovani . Also used to designate similar forms of Leishmania tropica found in macrophages in lesions of cutaneous leishmaniasis .

mamillary body (mammillary body) either of the pair of small spherical masses in the interpeduncular fossa of the midbrain, forming part of the hypothalamus. Masson b's cellular tissue that fills the pulmonary alveoli and alveolar ducts in rheumatic pneumonia; they may be modified Aschoff's bodies. molluscum b's large homogeneous intracytoplasmic inclusions found in the stratum granulosum and stratum corneum in molluscum contagiosum , which contain replicating virus particles and cellular debris. multilamellar body any of the osmiophilic, lipid-rich, layered bodies found in the great alveolar cells of the lung. Negri b's oval or round bodies in the nerve cells of animals dead of rabies . Nissl b's large granular bodies that stain with basic dyes, forming the reticular substance of the cytoplasm of neurons, composed of rough endoplasmic reticulum and free polyribosomes; ribonucleoprotein is one of their main constituents. Called also Nissl's granules . olivary body olive (def. 2). pituitary body pituitary gland .

polar b's 1. the small cells consisting of a tiny bit of cytoplasm and a nucleus; they result from unequal division of the primary oocyte (first polar body) and, if fertilization occurs, of the secondary oocyte (second polar body). 2. metachromatic granules located at one or both ends of a bacterial cell. psammoma b's usually microscopic, laminated masses of calcareous material, occurring in both benign and malignant epithelial and connective-tissue tumors, and sometimes associated with chronic inflammation. quadrigeminal b's corpora quadrigemina . body of sternum the second or main part of the sternum, bounded by the manubrium above and the xiphoid process below. Called also gladiolus and corpus sterni . striate body corpus striatum . trachoma b's inclusion bodies found in clusters in the cytoplasm of the epithelial cells of the conjunctiva in trachoma . vitreous body the transparent gel filling the inner portion of the eyeball between the lens and retina. Called also vitreous and vitreous humor . see corpus striatum. body surface area (BSA) the total surface area of the body.

Used to calculate drug dosages, particularly in the use of toxic drugs such as those used in cancer chemotherapy. This minimizes errors introduced by variations in distribution, metabolism and excretion of the drug. Several equations can be used to express the area, based on body weight, but conversion tables are usually used. See Table 21. trapezoid body transverse ridge crossing the ventral surface of the medulla oblongata. vitreous body the transparent gel filling the posterior segment of the eyeball between the lens and retina. Called also vitreous and vitreous humor. body weight an opacity of the vitreous which occurs with uveitis. vitreous floater a small opacity in the vitreous which may stimulate the retina and cause abnormal behavior patterns such as 'fly-biting'. vitreous humor 2. the watery substance contained within the interstices of the stroma in the vitreous body. peripapillary vitreous that adjacent to the optic disk. persistent hyperplastic vitreous a congenital anomaly, usually unilateral, due to persistence of embryonic remnants of the fibromuscular tunic of the eye and part of the hyaloid vascular system.

Clinically, there is a white pupil, elongated ciliary processes, and often microphthalmia; the lens, although clear initially, may become completely opaque. vitreous membrane Hyaloid body | Article about hyaloid body by The Free Dictionary Hyaloid body | Article about hyaloid body by The Free Dictionary [′vi·trē·əs ′bäd·ē] (physiology) Vitreous Body (1) The transparent gel that fills the eye cavity between the retina and the lens. The vitreous body is part of the eye’s dioptric medium, which transmits light rays to the retina. In humans, there are no blood vessels in the vitreous body of an adult. The liquid part of the body consists of viscous hyaluronic acid and traces of serum proteins, ascorbic acid, salts, and other substances; it is enclosed in a network of delicate protein fibrils. The vitreous body is surrounded by a hyaline film that firmly adheres to the macula retinae and the ciliary parts of the eye and in some animals, to other parts of the retina.

(2) The drug obtained from the vitreous body of the eyes of cattle; it belongs to the group of biogenic stimulants. Vitreous body is used subcutaneously in solutions to facilitate the resolution of scar tissue. It is also used in cases of joint contractures and as an analgesic in various disorders, including neuralgia and radiculitis. Hyaloid body - definition of hyaloid body by The Free Dictionary Hyaloid body - definition of hyaloid body by The Free Dictionary vitreous body n (Anatomy) a transparent gelatinous substance, permeated by fine fibrils, that fills the interior of the eyeball between the lens and the retina ThesaurusAntonymsRelated WordsSynonymsLegend: bodily fluid , body fluid , liquid body substance , humour , humor - the liquid parts of the body hyaluronic acid - a viscous mucopolysaccharide found in the connective tissue space and the synovial fluid of movable joints and the humors of the eye; a cementing and protective substance Want to thank TFD for its existence? Tell a friend about us , add a link to this page, or visit the webmaster's page for free fun content .

Link to this page: Copyright © 2003-2017 Farlex, Inc Disclaimer All content on this website, including dictionary, thesaurus, literature, geography, and other reference data is for informational purposes only. This information should not be considered complete, up to date, and is not intended to be used in place of a visit, consultation, or advice of a legal, medical, or any other professional. Hyaloid canal | definition of hyaloid canal by Medical dictionary Hyaloid canal | definition of hyaloid canal by Medical dictionary Related to hyaloid canal: hyaloid membrane , Cloquet's canal hy·a·loid ca·nal [TA] a minute canal running through the vitreous body from the optic disc to the lens, containing in fetal life a prolongation of the central artery of the retina, the hyaloid artery. See: vitreous , hyaloid artery . Synonym(s): canalis hyaloideus [TA], central canal of the vitreous , Cloquet canal , Stilling canal hyaloid canal a canal found in the vertebrate eye that passes through the vitreous humour from the lens to the blind spot.

Cloquet, Jules G., French anatomist, 1790-1883. Cloquet canal - a minute canal running through the vitreous from the discus nervi optici to the lens. Synonym(s): hyaloid canal Cloquet canal remnants Cloquet hernia - a femoral hernia perforating the aponeurosis of the pectineus and insinuating itself between this aponeurosis and the muscle, therefore lying behind the femoral vessels. Cloquet septum - the delicate fibrous membrane that closes the femoral ring at the base of the femoral canal. Synonym(s): femoral septum node of Cloquet - one of the deep inguinal lymph nodes located in or adjacent to the femoral canal. Synonym(s): Rosenmüller gland ; Rosenmüller node Stilling, Benedict, German anatomist, 1810-1879. Stilling canal - a minute canal running through the vitreous from the discus nervi optici to the lens.

Synonym(s): hyaloid canal Stilling column - Synonym(s): Stilling nucleus Stilling gelatinous substance - the central gray matter of the spinal cord surrounding the central canal. Synonym(s): central and lateral intermediate substance Stilling nucleus - a column of large neurons located in the base of the posterior gray column of the spinal cord, extending from the first thoracic through the second lumbar segment. Synonym(s): Stilling column ; thoracic nucleus Stilling raphe - the transverse interdigitations of fiber bundles across the anterior median fissure of the medulla oblongata at the decussation of the pyramidal tracts. canal a relatively narrow tubular passage or channel. accessory canal in the body of the basisphenoid bone, transmits the maxillary artery. alimentary canal the digestive tube from mouth to anus. See also alimentary canal. anal canal the terminal portion of the alimentary canal, from the rectum to the anus. atrioventricular canal the common canal connecting the primitive atrium and ventricle; it sometimes persists as a congenital anomaly. birth canal the canal through which the fetus passes in birth.

carotid canal one in the pars petrosa of the temporal bone, transmitting the internal carotid artery to the cranial cavity. carpal canal on the palmar surface of the equine carpus where the carpal groove is converted into a canal by the flexor retinaculum which stretches from the accessory carpal bone to the medial side of the carpus. It houses the flexor tendons. central brain canal lumen of the neural tube of the embryo within the brain. cervical canal the part of the uterine cavity lying within the cervix. condyloid canal in the occipital bone; transmits a vein. canal of Corti a space between the outer and inner rods of Corti. external ear canal the canal from the external auditory meatus to the eardrum. facial canal osseous tube in the temporal bone that transmits the facial nerve. femoral canal in the groin on the medial aspect of the thigh; contains the femoral artery and vein. c's of Gartner in the ventral wall of the vagina; they are remnants of the mesonephric ducts and very variable in their occurrence. Called also ductus epoophori longitudinales.

haversian canal see haversian canal. c's of Hering openings between the bile canaliculi and the cholangioles, the terminal ducts of the biliary duct system. Called also cholangiole . hyaloid canal central canal of the vitreous humor running from the lens to the optic disk. hypoglossal canal an opening in the occipital bone, transmitting the hypoglossal nerve and a branch of the posterior meningeal artery; called also anterior condyloid foramen. infraorbital canal a canal running obliquely from the front of the orbit to the side of the muzzle, transmitting the infraorbital vessels and nerve. In the horse it passes through the maxillary sinus. inguinal canal the oblique passage in the caudal abdominal wall on either side, through which passes the round ligament of the uterus in some females such as the bitch and the spermatic cord in the males. intestinal canal the nasolacrimal canal. lateral canal a small canal in the root of a tooth which emerges on the side, rather than the apex. Called also accessory canal.

mandibular canal a passageway within the mandible for conduction of the inferior alveolar vessels and nerve; the inferior alveolar nerve enters the mandibular canal through the mandibular foramen and exits at the mental foramen supplying nerves to the lower cheek teeth in passing. medullary canal 1. vertebral canal. 2. the cavity, containing marrow, in the diaphysis of a long bone; called also marrow or medullary cavity. metatarsal canal formed by the metatarsal fascia on the plantar aspect of the chief metatarsal bone of the horse; transmits the tendons of the digital flexor muscles. modiolar canal in the cochlea of the internal ear; it transmits blood vessels and nerves to the cochlea. nasolacrimal canal in the maxilla it transmits the nasolacrimal duct. nutrient c's large vascular canals through the cortex of bones. See also haversian canal. omasal canal the direct passage through the omasum from the reticulum to the abomasum. optic canal a passage for the optic nerve through the cranium into the orbit.

palatine canal formed by the maxilla and the palatine bone; transmits the palatine artery and nerve. pterygoid canal in the basisphenoid bone; contains the pterygoid nerve. root canal the part of the vertebral canal through the sacrum. Schlemm's canal the venous sinus of the sclera, a circular canal at the junction of the sclera and cornea that receives the aqueous humour. Called also scleral venous sinus. semicircular c's the canals (anterior, lateral and posterior) of the bony labyrinth of the ear. See also semicircular canals. spinal canal, vertebral canal the canal formed by the series of vertebral foramina together, enclosing the spinal cord and meninges. supraorbital canal in the frontal bone; transmits the frontal vein, passing through the zygomatic process to the orbital cavity. tarsal canal formed by the plantar annular ligament of the tarsus which roofs over the tarsal groove; transmits the deep digital flexor tendon and plantar vessels.

triosseus canal the foramen at the junction of the coracoid, clavicle and scapula which transmits the tendon of a flight muscle, the supracoracoideus, in the avian skeleton. vertebral canal spinal canal. Volkmann's c's canals communicating with the haversian canals, for passage of blood vessels through bone from the periosteum. Hyaloid canal - definition of Hyaloid canal by The Free Dictionary Hyaloid canal - definition of Hyaloid canal by The Free Dictionary Related to Hyaloid canal: hyaloid membrane , Cloquet's canal ca·nal 1. An artificial waterway or artificially improved river used for travel, shipping, or irrigation. 2. Anatomy A tube, duct, or passageway. 3. Astronomy One of the faint, hazy markings resembling straight lines on early telescopic images of the surface of Mars. tr.v. ca·nalled, ca·nal·ling, ca·nals or ca·naled or ca·nal·ing 1. To dig an artificial waterway through: canal an isthmus. 2. To provide with an artificial waterway or waterways.

[Partly French, channel, and partly Middle English, tube (from Medieval Latin canāle), both from Latin canālis, tube, channel, probably from canna, small reed; see cane.] canal 1. (Civil Engineering) an artificial waterway constructed for navigation, irrigation, water power, etc 2. (Zoology) any of various tubular passages or ducts: the alimentary canal. 3. (Botany) any of various elongated intercellular spaces in plants 4. (Astronomy) astronomy any of the indistinct surface features of Mars originally thought to be a network of channels but not seen on close-range photographs. They are caused by an optical illusion in which faint geological features appear to have a geometric structure vb (tr) , -nals, -nalling or -nalled, -nals, -naling or -naled 5. (Civil Engineering) to dig a canal through 6. to provide with a canal or canals [C15 (in the sense: pipe, tube): from Latin canālis channel, water pipe, from canna reed, cane1] ca•nal n., v.

-nalled -naled, -nal•ling -nal•ing. n. 1. an artificial waterway for navigation, irrigation, etc. 2. a tubular passage for food, air, etc., in an animal or plant; duct. 3. channel; watercourse. 4. one of the long, dark lines on the planet Mars, as viewed from Earth. v.t. 5. to make a canal through. [1400–50; late Middle English: waterpipe, tubular passage < Latin canālis] canal - The holes in a sponge are called canals. See also related terms for holes . canal I will have been canalling you will have been canalling he/she/it will have been canalling we will have been canalling you will have been canalling they will have been canalling Past Perfect Continuous Noun 1.

canal - (astronomy) an indistinct surface feature of Mars once thought to be a system of channels; they are now believed to be an optical illusion astronomy , uranology - the branch of physics that studies celestial bodies and the universe as a whole channel - a deep and relatively narrow body of water (as in a river or a harbor or a strait linking two larger bodies) that allows the best passage for vessels; "the ship went aground in the channel" 2.

canal - a bodily passage or tube lined with epithelial cells and conveying a secretion or other substance; "the tear duct was obstructed"; "the alimentary canal"; "poison is released through a channel in the snake's fangs" duct , epithelial duct , channel pore - any small opening in the skin or outer surface of an animal passageway , passage - a path or channel or duct through or along which something may pass; "the nasal passages" ductule , ductulus - a very small duct canaliculus - a small canal or duct as in some bones and parts of plants canal of Schlemm , Schlemm's canal , sinus venosus sclerae - a circular canal in the eye that drains aqueous humor from the anterior chamber of the eye into the anterior ciliary veins venous sinus , sinus - a wide channel containing blood; does not have the coating of an ordinary blood vessel ampulla - the dilated portion of a canal or duct especially of the semicircular canals of the ear lachrymal duct , lacrimal duct , tear duct - any of several small ducts that carry tears from the lacrimal glands nasolacrimal duct - a duct that carries tears from the lacr

imal sac to the nasal cavity Haversian canal - any of the many tiny canals that contain blood vessels and connective tissue and that form a network in bone hepatic duct - the duct that drains bile from the liver canalis inguinalis , inguinal canal - oblique passage through the lower abdominal wall; in males it is the passage through which the testes descend into the scrotum and it contains the spermatic cord; in females it transmits the round ligament of the uterus bile duct , common bile duct - a duct formed by the hepatic and cystic ducts; opens into the duodenum pancreatic duct - a duct connecting the pancreas with the intestine lymph vessel , lymphatic vessel - a vascular duct that carries lymph which is eventually added to the venous blood circulation salivary duct - a duct through which saliva passes from the salivary gland into the mouth aqueductus cerebri , cerebral aqueduct , Sylvian aqueduct - a canal connecting the third and fourth ventricles ureter - either of a pair of thick-walled tubes that carry urine from the kidney to the urinary bladder urethra - duct through which urine is discharged in most mammals and which serves as the male genital duct canalis cerv

icis uteri , cervical canal - a spindle-shaped canal extending from the uterus to the vagina umbilical , umbilical cord - membranous duct connecting the fetus with the placenta vagina - the lower part of the female reproductive tract; a moist canal in female mammals extending from the labia minora to the uterus; "the vagina receives the penis during coitus"; "the vagina is elastic enough to allow the passage of a fetus" epididymis - a convoluted tubule in each testis; carries sperm to vas deferens ductus deferens , vas deferens - a duct that carries spermatozoa from the epididymis to the ejaculatory duct seminal duct - the efferent duct of the testis in man ejaculatory duct - a part of the seminal duct formed by the duct from the seminal vesicle and the vas deferens; passes through the prostate gland cartilaginous tube - a duct with cartilaginous walls bronchiole - any of the smallest bronchial ducts; ending in alveoli The Vitreous Humor The Vitreous Humor Full Page View | Frames View | Main Page | Search Site | Home The vitreous humor is a clear gel which occupies the

 posterior compartment of the eye, located between the crystalline lens and the retina and occupying about 80% of the volume of the eyeball.

Light initially entering the eye through the cornea , pupil , and lens , is transmitted through the vitreous to the retina. Vitreous humor has the following composition: water (99%), a network of collagen fibrils, large molecules of hyaluronic acid, peripheral cells (hyalocytes), ascorbic acid. hyaloid artery The �hyaloid artery� (a branch of the primitive dorsal ophthalmic artery) grows, in the fetus, outward from the optic cup of the optic nerve into the vitreous cavity. It extend forward to the crystalline lens to aid its development. The hyaloid artery regresses during the last trimester of fetal formation, leaving behind the �Cloquet�s canal� through the vitreous. Sometimes, the hyaloid artery remains after birth and is viewable by a doctor looking into the eye as a �persistent hyaloid artery,� but it rarely is noticeable to the person who has it. Sometimes, remains of the lenticular attachment of the hyaloid artery can be found on the back surface of the crystalline lens. These tiny remnants appear gray or white and are located just inferior and nasal to the posterior pole of the lens.

These �Mittendorf�s dots,� which are congenital (present at birth), continue throughout life. They have no effect on vision. posterior vitreous detachment (PVD) With age, the vitreous humor changes from a gel to a liquid. As it does so, the vitreous mass gradually shrinks and collapses, separating and falling away from the retina. This is called a �posterior vitreous detachment� (PVD) and is a normal occurrence between ages 40 and 70. Commonly, a person having experienced a PVD will report seeing flashing lights and/or floaters in his or her field of vision. The flashes of light occur when the vitreous tugs on the sensory layer of the retina, as the vitreous is detaching. The floaters�which are cells or debris released, when the vitreous detaches�can appear as little dots, circles, lines, cobwebs, clouds, or a puff of smoke. Floaters can be apparent especially when looking at a bright background, as the light entering the eye casts shadows of the floaters onto the retina. Sometimes a large, single floater actually can obstruct print that is being read.

The observance of flashes and floaters can last two or more weeks. Episodes lasting even as long as six months can occur. It is said that the percent chance of having a vitreous detachment is at least the same as one�s age. However, a PVD may occur earlier than normal in moderately to extremely nearsighted people, as well as in people who have had cataract surgery. A dilated eye exam should be performed to make sure the symptoms are not due to a retinal detachment , which is a much more serious and potentially sight-threatening condition. floaters (muscae volitantes) As a posterior vitreous detachment (PVD) occurs�that is, as the vitreous fluid separates from the retina�organic debris or particles known as �floaters� are released. Another name for floaters is �muscae volitantes� (flying flies). Most floaters are merely compressed cells or strands of the vitreous gel which have clumped together so that they are less transparent than the rest of the vitreous. Some floaters are remnants of the hyaloid artery, which usually disintegrates before birth. These types of floaters are harmless.

Floaters sometimes interfere with vision, often during reading, and they can be quite annoying. If a floater appears directly in the line of sight, the best thing to do is to move the eye from side to side or up and down. Doing so can create a current within the internal fluids to move the floater temporarily away from the line of sight. If a floater is suspended in a portion of vitreous humor which is very viscous, it can be particularly persistent and bothersome. Unfortunately, in most instances, there is nothing to do but learn to tolerate the floater�s presence. Surgical removal, which is risky, is considered only in the most extreme cases. Usually, the vitreous makes a clean break as it pulls away from the retina. Rarely, however, the vitreous will adhere tightly onto the retina in certain places; and a small, often horseshoe-shaped rip in the retina can result from persistent tugging and tearing by the vitreous. Unless the retinal tear is repaired, fluid can seep through this hole into or underneath the retina and cause a retinal detachment , a very serious, sight-threatening condition.

As the vitreous membrane tugs on the retina, at points where the two structures remain attached, the tension can cause �flashing� sensations, because some of the retinal nerves are stimulated. Occasional flashes of light usually are nothing to be concerned about, unless they increase in frequency and/or occur in conjunction with a sudden onset of a large number of floaters. In this case, it may be that a retinal detachment has occurred. asteroid hyalosis Not uncommonly, tiny spherical or disc-shaped, �soapy� globs, can be located in the vitreous of one eye or occasionally in both eyes. This is known as �asteroid hyalosis.� When present, these calcium-containing lipid complexes usually are suspended throughout the vitreous. Usually, these �asteroids� are not observable by a person who has them, and they normally do not cause any decrease in vision, since light generally passes through them unaffected. Rarely, however, if the asteroids coalesce on the visual axis, especially at or near the nodal point immediately behind the lens, there can be a profound decrease in vision. In such a case, removal of the asteroids, via a vitrectomy, is an option to restore vision.

Return to the Main Page of Anatomy, Physiology & Pathology of the Human Eye Anatomy of Vitreous by Dr.Parthopratim Dutta Majumder | Vitreous Base | Hyalocytes | Cloquet Canal Anatomy of Vitreous by Dr. Parthopratim Dutta Majumder Vitreous is a transparent, colour less gel like structure which occupies the posterior compartment of the eye. It comprises about 80% of the total volume of the globe (two third of total volume of eye), about 4mL. The surfaces of the intraocular structures that interface with vitreous are mainly basement membrane in nature e.g.: pars plana of cilliary body, internal limiting membrane of retina and vitreous is attached to them with varying strength of adhesion. The word “vitreous” is derived from a Latin word “vitrum” which means glass. Attachments of vitreous: Vitreous is attached to its surrounding structures by condensation of collagen fibrils. From strongest to weakest, these are- Vitreous base-strongest Along the retinal vessels –Most variable and weakest Vitreous base The vitreous base is the place of strongest adhesion of vitreous.

Vitreous base forms a band of 4 to 6 mm width (1 to 2 mm anterior to the ora serrata and 1 to 3 mm posterior to it) which lies in the posterior aspect of the parsplana and adjacent anterior aspect of the ora serrata. There is strong adhesion between vitreous fibers of the vitreous base region and basement membrane of the nonpigmented epithelium of the cilliary body and internal limiting membrane of the periphery of the retina. Hyaloideocapsular ligament Hyaloideocapsular ligament of Weiger or Retrolental ligament is another strong adhesion of vitreous and posterior capsule of lens. It is a circular adhesion, 8-9 mm in diameter .The circular line of adhesion between vitreous and posterior lens capsule is often termed as “Egger’s Line”. The strength of this retrolental adhesion and peripapillary adhesion of vitreous decreases with age. Within this circle, there lies a potential space of nonadhesion between vitreous and lens, known as space of Burger or Erggelet's space.

(Also read Anatomy of Lens ) Vitreous is attached with the macula in an annular fashion with a diameter of 3 -4 mm.It is also attached alongside the larger retinal vessels. For description purpose, vitreous can be divided into a outer zone and central zone. Outer zone of vitreous: The outermost zone of vitreous is also known as the cortex. Most of the vitreous collagens are located in cortex and these collagen fibrils run parallel & perpendicular to retinal surface. The shape of the vitreous is just like a sphere with an anterior depression which is known as patellar fossa or lenticular fossa or hyaloid fossa which supports the lens. Anterior surface of the vitreous is known as anterior hyaloid face which clinically behaves like a membrane. Central zone: The central zone has little collagen compared to outer vitreous and physically more liquid than the outer zone of vitreous. In this region, vitreous cells (hyalocytes) are less in number and collagen fibrils are thinly scattered. Cloquets Canal: The central vitreous is traversed by a canal which is known as cloquet or hyaloid canal or retrolental tract.

It extends from the posterior surface of the lens to the optic nerve head. Basically it represents the remnants lumen of the course of hyaloid artery during embryogenesis. This space is devoid of collagen fibrils. It is 1 to 2 mm in diameter and “S” shaped from anterior to posterior. Cloquet canal is named after French anatomist Jules Germain Cloquet (1790-1883) It starts from patellar fossa as a widening and after taking an “S” shaped course in central vitreous, again widens near the optic nerve head to form space of Martegiani. A remnant of incomplete atrophy of the hyaloid artery may be seen in this location and is called Bergmeister's papilla. With age, the firm attachment of vitreous with optic nerve head loosens. When vitreous detaches completely, this peripapillary attachment becomes visible clinically as a partial or complete annular ring, which is known as Vogt or Weiss ring. Hyalocytes or Vitreous Cells: Though vitreous is an acellular structure, hyalocytes or vitreous cells are found in cortex adjacent to retina and cilliary body.

They are found near the vitreous base, over the optic nerve head and in close proximity to the retinal vessels. Hyalocytes are basically mononuclear phagocytes or macrophages. Few fibrocytes and glial cells are also seen in vitreous.

Question: Where in the body is the Hyaloid canal?
Answer: Eye